Appliance for introducing flex into a cable sheath for the subsequent introduction of an electric cable

ABSTRACT

The device is shown here in a three dimensional view at an angle to the front. It is of very simple design and essentially consists of a fan ( 1 ), with a blower pipe ( 2 ) and a holding container ( 3 ) for a hollow cylindrical cord reel placed around the blower pipe ( 2 ). This cord reel ( 4 ) can be seen here because the holding container ( 3 ) is made from a polycarbonate section of tubing, thus providing a view of its interior. The cord reel ( 4 ) consists of a cable insertion cord. Along its cylindrical axis, the cord reel ( 4 ) exhibits a free space ( 5 ), from which the cord ( 6 ) is gradually spooled radially to the outside. At the holding container&#39;s ( 3 ) front end, it is sealed to a flange ( 8 ), which carries a nozzle ( 10 ). When running, the fan conveys air through the device axially, so that the cord ( 6 ) is carried along too and thereby unwound from its reel ( 4 ) and thence through the nozzle ( 10 ) to the outside and then through a connected cable conduit of whatever length and even having many twists and turns.

This invention refers to a device for inserting a cord into a cableconduit, so that subsequently and with the aid of this cord, anelectrical cable can be drawn into the empty cable conduit laid.

Almost everywhere that electric cabling is to be laid in buildings,empty plastic cable conduits are first laid and these are then embeddedin concrete or otherwise covered over. It is only at a later phase inthe construction work, namely once the building has been erected, thatelectric wiring or cables are drawn into these empty cable conduits. Thepre-installed plastic conduits have an inner diameter of a fewmillimetres and are smooth on the inside, however some have a groovedsurface and these are known as flexible conduits. The grooves run aroundthe circumference of the conduit's section, making it easier for them tobe laid around tight curves without running the risk of creating ahollow where the conduit is depressed, which will make the subsequentpulling through of a cable more difficult or even impossible.

Subsequent insertion of an electric cable generally presents no problemsfor short runs of conduit and where they run more or less in a straightline. However, where the empty conduit is particularly long, say 10 or20 metres and more, and above all if it is laid along a lot of tightcurves, insertion of an electric cable is often problematical. Theprocedure is that first an insertion strip in the form of a flexiblenylon rod with a thickness of 2-3 mm and a length of up to 20 metres isfed into the empty conduit and pushed right through until its tip comesout at the other end. At the lower end, an electric cable can beattached and then drawn through the conduit by pulling on the tip of thenylon rod. If an empty conduit should be particularly long or passthrough many curves, or both, then the insertion of the rod by pushingit from one end will no longer be possible. Its tip will either beblocked by too tight a curve or the friction will simply become so greatthat the rod cannot be pushed through until its tip emerges at the otherend. In this event, assistance can be provided by a vacuum cleaner: Thisis attached and sealed to the far end of the conduit and suction appliedto the air inside. At the lower end a cord is inserted and this is thentaken up and carried along by the airflow and in this way it can easilybe pulled through over big distances and around many curves, until itstip emerges into the vacuum cleaner's bag. If suction continues to beapplied and more cord is fed in, then the further end of the cord willsimply collect in the vacuum cleaner bag. The nozzle of the vacuumcleaner can be removed from the conduit and the surplus cord can then bewithdrawn from the vacuum cleaner's bag. With the aid of this cord, theelectric cable can either be pulled directly into the conduit, or usedfirst to pull through a nylon rod, the so-called insertion strip. Oncethe insertion strip has been pulled into the conduit, the insertion ofan electric cable presents no further problems: It is simply attached tothe end of the rod and pulled with this through to the end of theconduit. However, the employment of a vacuum cleaner is not particularlypractical for various reasons.

The first consideration is that the vacuum cleaner applies suction. Thismeans that it must have an airtight connection to one end of the conduitand the cord then has to be inserted at the conduit's other end, so thatsuction can be applied to the cord from one end of the conduit, by meansof the vacuum cleaner. If the conduit in a given building runs aroundmany corners and/or through several storeys, then the usage of a vacuumcleaner is particularly laborious if a single electrician is carryingout the installation work. In this case, he has to first connect thevacuum cleaner then go to the other end of the conduit to feed in thecord. After this, he has to go back to the vacuum cleaner and connect itto the conduit next in line and so on. If many conduits are involvedthat each require a cord to be inserted, then many actions are involved:The fitter will need to keep going back and forth between the two endsof the conduits. For this reason, it is preferable for the electriccables to be installed by two fitters. By employing a vacuum cleanerthen, the insertion of a cord must basically be worked on from both endsat the same time. If conduits should emerge at points where access ispoor or perhaps in a ceiling, then the connection of a vacuum cleanernozzle often presents problems. In addition, a vacuum cleaner is a heavyand bulky piece of equipment for carrying out this work. After all, itwas not actually designed and intended for inserting cords intoconduits. In the state of the art a blower pistol is disclosed in EP 0277 029 A (COMMW IND GASES) of 3 Aug. 1988. This pistol comprises amanual valve for controling the gas flow from a pressure air source. Thegas is supplied by a pressure source, namely from a gas cylinder, e.g.from a cylinder which is filled with carbiondioxid. DE 12 26 673 B(ROLAND SCHEUCHZER DR) of 13 Oct. 1966 discloses a device that workswith a pressure source whereby the pressure air is lead by a pressureline to the device and which does push a cork through the conduit pipewhich cork does then pull the cord into the conduit pipe. U.S. Pat. No.6,264,170 B1 (CASELLA DAVID WAYNE) of 24 Jul. 2001 discloses a pneumaticpistol which also works with pressure aire of a pressure source. Allthese devices require the supply of pressure air.

For this and other reasons, the inventive task has been to create adevice, by means of which the insertion of cables into conduits can bemade easier without the need of a pressure air source which doesfacilitate the pulling in of cables on site substantially. This deviceis intended to enable a more practical way of working than was hithertoemployed for the insertion of cables. The insertion of a cord is to beable to be carried out just from one end of the conduit. In addition,the device is to be light and handy, so that it can be connected to lessaccessible conduit openings. By using this device, a cord is to beparticularly easily and quickly inserted into a conduit, so that it canthen drag a cable or a rod in directly, by means of which an electricalcable can finally be pulled into the conduit.

This task will be solved by a device for inserting a cord into a cableconduit for the purpose of subsequently pulling through an electricalcable, comprising a hollow cylindrical holding container for taking acord reel to be unwinded, an outlet nozzle for the outlet of the cord anthe front side of this holding container and a housing at the backsideof the holding container, the housing being equipped with a handle inthe form of a pistol-like grip, and a push, toggle or rocker switch,characterized in that a blower pipe or a rod extends axially through thecomplete hollow and cylindrical holding container and projects into theoutlet nozzle, whereby a cylindrical cord reel with cylindrical outerside and for unwinding from inside fits with its outer diameter into theholding container and with its central free space over this pipe or thisrod, such that the pipe or rod does cross the inserted cord reelcompletely and remains spaced from the cord reel around itself, furtherthat the housing behind the holding container contains an electricalfan, the air current produced by this fan being able to pass from thebackside of the holding container through the pipe or on its outer sidealong the pipe or rod and henceforth through the outlet nozzle on thefront side of the holding container to the outside, so that this currentof air continually unwinds cord from the inner side of the reel andtakes it out through the nozzle.

The illustrations show such a device in a sample design, followed by adescription where its function is explained with reference to theseillustrations.

They show:

FIG. 1: A three dimensional drawing of the device

FIG. 2: The device in longitudinal section

FIG. 3: A side view of the device

FIG. 1 shows a three dimensional view of the device at an angle to thefront right hand side. The device's design is very simple andessentially consists of a fan 1 with a blower piper 2 and a holdingcontainer 3 placed around the blower pipe 2 for a hollow cylindricalcord reel 4. This cord reel 4 can be seen here because the holdingcontainer 3 is made from a transparent polycarbonate or Plexiglas pieceof tubing, thus providing a view of the interior. The cord reel 4inserted in the holding container 3 has the shape of a hollow cylinder,so that it therefore exhibits a free space 5 along the axis of thecylinder, from which the cord 6 is gradually (i.e. layer by layer)spooled radially to the outside. This cord reel 4 contains a cableinsertion cord. The reel's dimensions are about 110 mm in diameter and100 mm in length, with a free space having a diameter of some 30 mm. Atthe front end, the tubular holding container 3 is bonded to a flange 7,which in relation to the outer surface of the holding container 3 formsa radial projection. A further flange 8 is mounted on this projectionand screwed to the holding container 3, along with the first flange 7.This outer flange 8 has a hole at its centre that is bigger than thediameter of the blower pipe 2. A socket 9 is fitted to this flange'shole and in this a nozzle 10 is inserted. The blower pipe 2 stretchesfrom the fan 1 right through the whole holding container 3 and extendsabout half way into the socket 9. At the rear of the fitted flange 8,not visible here, there is a retaining ring 11 separated from it bymeans of supports 12, which keeps the cord reel 4 back, so that it isalways situated next to the fan 1. The unreeled cord 6 then runs insidethe cord reel 4 along the outside of the blower pipe 2 and is thencarried in the front part of the device, between the outside of theblower pipe and the inside of the socket 8 into the inside of the nozzle10 and finally exits to the outside at the front end of the nozzle 10.An electrical power cord 13 leads to the fan to power the fan's motorand on the outside of the fan 1, i.e. mounted on its housing, is ahandle 14, which here forms two opposing grips. Fitted to the housing 1above the handle 14 is a push, toggle or rocker switch 20. The handle 14can be held in a pistol-like grip as indicated on the drawing andleaving the forefinger able to operate the switch 20. Because the handleis shaped like a letter W, it can be grasped like a pistol grip bothfrom the front and from behind. In addition, the shape it forms protectsthe switch 20 from damage.

FIG. 2 shows a longitudinal section of this device, though contrary toFIG. 1, the view is from the other side. On the basis of this sectionaldrawing, the device's design can be understood in detail: On the rightof the image, the fan 1 is to be seen, which is contained in a hollowcylindrical casing 15. This casing 15 is closed front and rear by anannular bezel cap 16 & 17. The bezel 16 at the back of the devicecarries a socket-shaped air intake socket 18, in which a mesh grid 19 isemployed, say of a 1 mm gauge, so that no larger objects can be suckedinto the fan during use. On the other side of the fan there is a centralhole in the annular bezel 17, into which the blower pipe 2 is insertedand sealed or screwed in. On the other side of this annular bezel 17 andthus inside the housing, the actual fan is mounted. This is just acommercially-available vacuum cleaner fan with a power rating of say840W. Obviously, other types of fan can be used with a higher or lowerpower output. However, in practice it has been revealed that a vacuumcleaner fan of about the rating mentioned is completely sufficient.

A handle 14 is fitted to the bottom of the casing 14, which with its twoloops projecting downwards form a grip, enabling each loop to be graspedand held by one hand like a pistol grip. On the fan's housing, above thehandle 14 and at its centre, a switch 20 is fitted, which can beconveniently operated by the index finger of the hand holding thedevice. The switch 20 has the advantage of being a rocker switch that issprung loaded and can be rotated around from its vertical position intwo directions and which then doses the circuit, thus powering the fanand setting the fan's motor in motion. However, a toggle switch is alsosuitable for use as the switch 20 and this will retain its on positionwhen operated, having to be actively moved back to its neutral position.A push-button switch is also conceivable and this only closes the powercircuit when it is pressed.

In the picture, the hollow cylindrical cord reel 4 has been placed overthe blower pipe 2 from the left, so that it then encloses the blowerpipe 2 with its inner space, but leaving a small gap between its insideand the blower pipe of some 1 to 2 mm. The cord reel 4 is enclosed by aholding container 3 that is preferably to be made from a piece ofPlexiglas or polycarbonate tubing, because Plexiglas will provide a viewof the interior of the holding container 3, making it possible to checkat any time whether the cord reel 4 still has sufficient cord forfurther use. At the front end of the holding container 3 sits the flange7, which forms a radial projection from the Plexiglas tube. A furtherflange 8 with a central hole is screwed on to this projection, abovewhich a socket 9 is placed at the front. On the rear side of the flange8 a number of supports 12 extend into the holding container 3 and carrya retaining ring on their ends. This retaining ring 11 ensures that thecord reel 4 is always pushed against the cover 17 on the fan housing. Atthe same time, the blower pipe 2 extends a little into this socket 9. Atthe front, a circular groove 25 has been cut out of the inside of thesocket to accommodate an O-ring. A nozzle 10 is inserted into thissocket 9 and this is sealed in the socket 9 by the O-ring, forming afunnel-shaped extension 21 inside in the area of the blower pipe'sopening. At the leading edge, the nozzle 10 has been given a straightbore 22 that at its outer end has a wider bore 23 with an annular groove24 for accepting, securing and sealing a socket. A helical groove 26 hasbeen machined out of the outer side of the nozzle. The socket 9 isinterspersed by a radially-drilled bore 27, through which a bolt (notshown here) is passed and which projects into the groove 26 on thenozzle 10. By rotating the nozzle 10 it is wound more or less in or outof the socket. When wound in, the funnel-shaped inner wall clamps thecord to such an extent that it cannot be carried through any more by theair current.

If the electric fan's motor is now switched on, then an air current willbe generated through the device. At the back, where the air intakesocket 19 is, air will be sucked in and pass along the blower pipe 2,then to be expelled at its front opening through the nozzle 10. The cord6 from the reel 4 runs as shown on the drawing from the inside of thecord reel 4, along the outside of the blower tube 2 to its opening andfrom there through the nozzle 10 to the outside. It is carried on by theprevailing air current and thus continually unreeled from the cord reel4 and conveyed to the outside. However, if the nozzle 10 is rotatedclockwise as viewed from the front of the device, then it will bescrewed into the socket 9 and its funnel-shaped interior will clamp thecord between it and the outside of the blower pipe's opening, so thatthe cord can no longer continue to be transported. This clamping actionis so strong then that the prevailing air current is no longer capableof unwinding the cord from its reel 4 and conveying it to the outside.This function is required occasionally, should the device be used merelyfor blowing through an empty conduit for the purpose of identifying itsother end: Air is blown through, and if at the other end, which may bein another room or on another level of the building, air is expelledthen this will permit the relevant conduit to be identified, in theevent that several conduits have been run in parallel through thebrickwork.

In FIG. 3, the device is to be seen in side view. At the front on thenozzle 10, a flexible tube 28 has made from plastic has been attached asan adaptor. This flexible tube 28 has the advantage of being made fromcommercially-available coolant hose, as is used on machine tools forconveying coolant. With its pointed opening, this flexible tube 28 canalso form a sealed connection on less accessible conduits. In onevariant, even a closed pipe or a rod can replace the blower pipe 2 thatruns through the holding container 3 and over which the cord reel 4 isplaced with its free space. Air will not then be blown through the pipeitself, but will flow outside and along it or the rod in an axialdirection through the cord reel. In the version shown in FIG. 2, the airfrom the fan could then even enter through holes or bores in the bezel17 into the holding container 3 and flow around this in an axialdirection along the pipe 2, whilst the interior of the pipe 2 would beclosed off. Additionally, the air does not have to be blown, but merelyconveyed. Therefore an arrangement would be conceivable, in which thefan, in relation to FIG. 2, would not be behind the holding containerbut in front of it, so that the air would be sucked along a central pipeor rod, or through a central pipe, which would lead through the fan,after which the air would then pass through a nozzle at the end of thefan.

In order to insert a cord into a conduit, the end of the cord emergingfrom the flexible tube 28 is eased into it then the device applied tothe conduit by means of the flexible tube 28, forming a seal against it.Then the switch 20 is operated and straight away the cord will be blowninto the conduit. It will be carried along by the air current generatedthrough the whole length of the conduit, no matter how long it may beand how many curves it negotiates or how tight they are. Tests haveshown that it can even be inserted through a whole roll of conduit, i.e.in the lengths that conduit is stored and sold. However the device canalso be used in the identification of conduits that have been laid. Toachieve this, the nozzle is rotated so as to form a brake for the cord.Now the device can be used just for blowing nothing but air. Thereforeit is a simple matter to apply blown air quickly to several conduitopenings of a whole bundle of conduits, one after another. To achievethis, it is best that the conduits are numbered, and each conduit isblown in ascending numerical order. An assistant at the opposite end ofthe bundle will then number the openings, one after the other and in theorder in which the air flows out. This way it is possible to identifywhich openings are connected with one another. The device can also beused for applying suction. To achieve this, a cord is inserted from theopening at the opposite end and the device is connected to the openingat this end, using a suction coupling. In this case, the cord is pulledalong by the current of air formed by the suction. When it emerges onthis side, i.e. at the opening where the device is located, it willcollect at the mesh grid in the air intake. By this means, the latterwill become almost completely blocked after a short time, which willbecome noticeable by a change in the sound of the fan or the motor. Thisway, it will be immediately known that the cord has arrived at thedevice and that it has passed through the whole of the conduit.

This device enables work to be undertaken in a very practical manner. Inparticular, the insertion of a cord from one end only can be carried outby a single operative. In addition, the device is light and handy andcan therefore be connected to less accessible conduit openings and inparticular to those with their openings in a ceiling. By means of thisdevice, a cord can be inserted into a conduit particularly easily andquickly, so that it can then pull through an electric cable directly, ora rod first, which in turn will be used to pull an electric cablethrough the conduit.

1-10. (canceled)
 11. An apparatus for inserting a cord into a cableconduit for subsequently pulling through an electrical cable,comprising: a housing having a handle with a pistol-like grip and apush, toggle or rocker switch; a hollow cylindrical holding containerfor taking a cord reel to be unwinded, said housing being at a backsideof said hollow cylindrical holding container; an outlet nozzle for anoutlet of cord at a front side of said hollow cylindrical holdingcontainer; a blower pipe extending axially through said hollowcylindrical holding container and projecting into said outlet nozzle, sothat a cylindrical cord reel having a cylindrical outer side, and forunwinding from inside, fits with its outer diameter into said hollowcylindrical holding container and with a central free space over saidblower pipe, wherein said blower pipe completely crosses an insertedcord reel and remains spaced from the cylindrical cord reel arounditself; and, an electrical fan within said housing for producing an aircurrent capable of passing from the backside of said hollow cylindricalholding container through said blower pipe, or on its outer side alongsaid blower pipe, and through said outlet nozzle on the front side ofsaid hollow cylindrical holding container to an outside area, so thatsaid air current continually unwinds cord from an inner side of saidcord reel and takes the cord through said outlet nozzle.
 12. Theapparatus for inserting a cord into a cable conduit for subsequentlypulling through an electrical cable according to claim 11, wherein saidblower pipe extends axially through said hollow cylindrical holdingcontainer and through said central free space of the inserted cord reeland ends in an inner side of said outlet nozzle.
 13. The apparatus forinserting a cord into a cable conduit for subsequently pulling throughan electrical cable according to claim 12, wherein said hollowcylindrical holding container is attached to a flat side of said housingcontaining said electrical fan and comprises a pipe section having aflange at one end, with said blower pipe crossing said pipe section andprotruding therefrom and with said flange being attached onto saidflange via a central hole, bearing a spaced retaining ring on its innerside for sup-porting the inserted cord reel and, on its outside, saidoutlet nozzle for the cord.
 14. The apparatus for inserting a cord intoa cable conduit for subsequently pulling through an electrical cableaccording to claim 12, wherein said outlet nozzle is sealed into asocket, which is fitted to a flange, with said outlet nozzle having acircular groove on an outer side for permitting radially interspersedbolts are engagable in said socket.
 15. The apparatus for inserting acord into a cable conduit for subsequently pulling through an electricalcable according to claim 12, wherein said pistol-like grip of saidhandle of said housing is operable via a user's index finger of a handenclosing said pistol-like grip.
 16. The apparatus for inserting a cordinto a cable conduit for subsequently pulling through an electricalcable according to claim 12, wherein said housing is made from a plastictubing and said handle is made from a wire loop with two angled loopspointing downwardly, so that said wire loop creates two grip handlesopposite one another.
 17. The apparatus for inserting a cord into acable conduit for subsequently pulling through an electrical cableaccording to claim 12, wherein said electrical fan has a rear sideclosed by an annular bezel with a central hole and with an air intakesocket placed around the central hole, which is internally equipped witha mesh grid.
 18. The apparatus for inserting a cord into a cable conduitfor subsequently pulling through an electrical cable according to claim12, further comprising a vacuum cleaner motor for driving saidelectrical fan, said vacuum cleaner motor having an electrical output of700 to 1,400 watts.
 19. An apparatus for inserting a cord into a cableconduit for subsequently pulling through an electrical cable,comprising: a housing having a handle with a pistol-like grip and apush, toggle or rocker switch; a hollow cylindrical holding containerfor taking a cord reel to be unwinded, said housing being at a backsideof said hollow cylindrical holding container; an outlet nozzle for anoutlet of cord at a front side of said hollow cylindrical holdingcontainer; a rod extending axially through said hollow cylindricalholding container and projecting into said outlet nozzle, so that acylindrical cord reel having a cylindrical outer side, and for unwindingfrom inside, fits with its outer diameter into said hollow cylindricalholding container and with a central free space over said rod, whereinsaid rod completely crosses an inserted cord reel and remains spacedfrom the cylindrical cord reel around itself; and, an electrical fanwithin said housing for producing an air current capable of passing fromthe backside of said hollow cylindrical holding container through saidrod and through said outlet nozzle on the front side of said hollowcylindrical holding container to an outside area, so that said aircurrent continually unwinds cord from an inner side of said cord reeland takes the cord through said outlet nozzle.